• WeX
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Topic: Graph in interval to repeat it self

Hi there.
I need to create a graph that is limited by an interval, which i know how to do.
My problem is, that i have a function with three intervals, which are the three steps in a Timeperiode.
This means that, when the timeperiode is over i need the function to repeat it self!

How do i solve this(if possible at all)?

Best regards WeX

Re: Graph in interval to repeat it self

By using the if function you can specify intervals as part of the expression like f(x)=if(0<x<pi/2 or pi<x<2pi, sin(x)), which will plot sin(x) for the two intervals 0<x<pi/2 and pi<x<2pi.

  • WeX
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Re: Graph in interval to repeat it self

Ivan Johansen wrote:

By using the if function you can specify intervals as part of the expression like f(x)=if(0<x<pi/2 or pi<x<2pi, sin(x)), which will plot sin(x) for the two intervals 0<x<pi/2 and pi<x<2pi.

That i do know, and a trigonomic function, would if no limited continue endless.
How ever that is not what i need.
I wish to create a triangle function, wich got the same characteristics as fx a sinus function(such as peak to peak value, periode, phase and so on). Where as the sinus function would be one smooth kurved line, the triangle function would be the same function basically, but just with straight lines from peak to peak.

Re: Graph in interval to repeat it self

I am not sure exactly what you want to do, but maybe you want to plot a sawtooth wave or a triangle wave:

f(x)=mod(x, 5)
f(x)=abs(mod(x,5)-2.5)

Re: Graph in interval to repeat it self

Maybe you want the periodic extension of a function g defined on an interval [a,b].  If so, define p(x)=a+mod(x-a,b-a).  (This is the identity function on [a,b] and is periodic with period b-a.)  Then the function f(x)=g(p(x)) is the periodic extension of function g.  The attached file shows one example g and it's extension.

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Attachment icon periodicextension.grf 704 b, 496 downloads since 2012-11-13